During pregnancy the entrance to the uterus, the cervix, is sealed by a thick mucous plug, which helps to protect the contents of the uterus from any infection.
They DO go inside the uterus during a D&C, otherwise it can not be performed. The C stands for curettage which is scraping the uterus wall with a tool called Curette.
The baby easily "survives" inside of the mother's body. Seeing as this is the way nature intended children to be born, there are several ways the mother nurtures her unborn child, these are just a...